Silicon carbide (SiC) has a high electric field property to dielectric breakdown, and a wide band gap in comparison with silicon (Si). For this reason, a semiconductor device using silicon carbide (hereinafter, referred to as a “silicon carbide semiconductor device”) has a feature of low resistance and the capability to operate at high temperatures in comparison with a semiconductor device using silicon, and thus expected as a next-generation power semiconductor device.
There is, for example, a MOSFET, a Schottky diode or a like element as such a silicon carbide semiconductor device in which an electric field concentrates in its termination end-portion provided in a perimeter of the element. When the electric field concentrates in the termination end-portion as described here, a voltage-withstand characteristic of the silicon carbide semiconductor device is lowered. For this reason, in order to relax the electric field concentration in the termination end-portion, to obtain sufficient capabilities of the silicon carbide semiconductor device, an electric-field relaxation structure such as a JTE (junction termination extension) or MFGR (multiple floating guard ring) structure is provided in the termination end-portion.
In addition, in order to secure reliability of the silicon carbide semiconductor device over a long period of time by stabilizing the characteristic thereof, a protection film is formed to constitute the top side of the termination end-portion having the electric-field relaxation structure such as a JTE or an MFGR.
As for such a protection film, it is generally taking place to use an oxide film, for example, as disclosed in Patent Documents 1 through 3.
In addition, the protection film using a polyimide film is disclosed in Non-Patent Document 1.
[Patent Document 1]
Japanese Laid-Open Patent Publication No. 2003-282888
[Patent Document 2]
Japanese Laid-Open Patent Publication No. 2007-103524
[Patent Document 3]
Japanese Laid-Open Patent Publication No. 2004-363518
[Non-Patent Document 1]
“2nd Generation” SiC Schottky diodes: A new benchmark in SiC device ruggedness, Proceedings of the 18th International Symposium on Power Semiconductor Devices and IC's, Jun. 4-8, 2006, Naples, Italy